The Story

An off-duty Dawson and Casey help other volunteers at a "Chicago P.D. and Chicago F.D. Race Against Cancer" event held outside Chicago Medical. Officer Burgess, with her nine-year-old niece, Zoe, in tow, joins them to help set up a tent, along with Dr. Holly Thelan and her nine-year-old sister Imogene. With everything in order, Dawson decides to register for the race and heads into the building... moments later a bomb detonates! The blast tears a hole into the hospital, sprays concrete into the streets and injures dozens, including Zoe and Imogene. Once the initial shock wears off, Casey scrambles to help the two girls while realizing Dawson's likely trapped inside the rubble.

Boden and the squad arrive and hit the ground running, coming to the aid of the wounded while rescuing stranded individuals from the race and from within the hospital. Judging from the blast, Mills reckons a car bomb did the damage, which can only mean one thing: there are other explosives out there. He and Cruz find exactly that in the adjacent parking structure, where Mills puts his rescue squad training to the test, boldly tugs at a live wire - and diffuses the bomb!

Another close call occurs as Shay avoids falling debris only to puncture her side on a piece of rebar. Her old partner, Rafferty, filling in for Dawson, doesn't notice, so Shay keeps the wound a secret and patches it up in private in order to continue helping the cause. But the longer she goes the more it appears that the wound could be worse than she imagined...

Meanwhile, Dr. Arrata discovers that Zoe suffered a crushed liver and needs an operation. In the unaffected hospital wing, he operates on the young girl as Burgess waits outside the door, wrecked with nerves. But the operation proves unsuccessful; Zoe requires a full transplant. Dr. Arrata scours the hospital for a replacement and manages to find one - except it turns up damaged and unusable. He delivers the tough news to Burgess, who crumples the floor, devastated that her niece may not survive. Not even Burgess' partner Atwater can console her.

To make matters worse, Imogene goes from visibly fine to a full-on seizure. A quick prognosis determines her brain swelled from a concussion she sustained in the blast and she enters the operating room in an unconscious state. Doctors operate to relieve the pressure, desperate not to lose two young lives on the same day...

All this unfolds as Casey and Severide dive into the dark trenches of the rubble in search of Dawson. Despite their constant calls, they hear no response. Is she dead, like so many others? On the other side of the rubble, Dawson stirs - weak and in pain. Unable to muster a scream to alert them to her whereabouts, she knocks two metal poles together. The rhythmic noise leads Casey and Severide to her location and, with Herrmann's help removing the slabs of concrete from above, they lift Dawson out. The whole team celebrates.

On the tail of this momentary relief comes the rest of Chicago P.D. - and members of the FBI. Voight targets a suspicious group of diplomats from Syria, ostensibly in town for their ambassador's off-the-books liver transplant. Is this their first lead?

With things finally calming down from the blast, Shay's adrenalin ebbs and, in front of Burgess and Atwater, she collapses to the floor, unconscious and bleeding from her earlier wound...